Dear all: am asking about kiln shutdown program?it's necassary to stop pH fan when feed stop
Engr
Dear Elwathig,
For a small stoppage, what I suggest to run PH fan with min speed with damper close b/c when ever feed stop, it will cause high T to reach PH fan inlet hece your fan should be in a running condition to avoid irregular thermal expansion of impeller but for a long shutdown when u think that Prehtr top T are below 200 C then u can stop PH fan for power saving and maintain draft by Exhaust Bag House fan.
But in both cases, always avoid high T at PH fan inlet and impeller should have a slight movement.
Thanx, have a nice day.
EngrS
elwathig
deal:sir
in our plant when there are going to stop kiln for long time shutdown immediately will stop PH fan and kept only bag house running with low speed? in the last shutdown :
the kiln was running with feed:280tph ,speed:3.1rpm ,PH fan speed:680rpm ,Bag house fan:600rpm and PH fan inlet temp :320C .
the operating temp: 400C max
max bearing temp :80C
what happened the opeator stopped ph fan and open damper 20% after 30mints the inlet temp reach 400C and bearing temp;85c
1-my guestion is this decision in the proper place?
2-and pls give me the solutions for this cases?
3-for short shutdown it"s necassary to stop ph fan?
Engr
Dear Elwathig,
Decision taken by operator looks ok b/c in most of plants, PH fan stoppage is interlock with kiln feed stop/tripping.
If you are not able to control the PH fan inlet temp then donot open the PH fan damper. For cooling the preheater gases, carefully open the doors of Top cyclones to exhaust the hot gases. Never exceed your bearing TMax limit, it will shorten the life of bearing. or even damage it. (Some plants are having exhaust damper at preheater top for this purpose)
For short stoppages, you can stop PH fan or run with min speed. Not necessary to stop PH fan.
Have a nice day
EngrS